This invention relates generally to radar and communication systems and more particularly to an active phased array radar system operating in the Ka-band above 30 GHz.
Active electronically scanned antenna (AESA) arrays are generally well known. Such apparatus typically requires amplifier and phase shifter electronics that are spaced every half wavelength in a two dimensional array. Known prior art AESA systems have been developed at 10 GHz and below, and in such systems, array element spacing is greater than 0.8 inches and provides sufficient area for the array electronics to be laid out on a single circuit layer. However, at Ka-band (>30 GHz), element spacing must be in the order of 0.2 inches or less, which is less than 1/10 of the area of an array operating at 10 GHz.
Accordingly, previous attempts to design low profile electronically scanned antenna arrays for ground and air vehicles and operating at Ka-band have experienced what appears to be insurmountable difficulties because of the small element spacing requirements. A formidable problem also encountered was the extraction of heat from high power electronic devices that would be included in the circuits of such a high density array. For example, transmit amplifiers of transmit/receive (T/R) circuits in such systems generate large amounts of heat which much be dissipated so as to provide safe operating temperatures for the electronic devices utilized.
Because of the difficulties of the extremely small element spacing required for Ka-band operation, the present invention overcomes these inherent problems by “vertical integration” of the array electronics which is achieved by sandwiching multiple mutually parallel layers of circuit elements together against an antenna faceplate. By planarizing T/R channels, RF signal manifolds and heat sinks, the size and particularly the depth of the entire assembly can be significantly reduced while still providing the necessary cooling for safe and efficient operation.